Bring a large pot of water to a boil and drop in the green beans. Simmer over medium-high heat until beans are just barely cooked and still bright green, about 2 minutes. Drain immediately and rinse under cold water. Drain and set aside.

Heat oil in a skillet over medium heat. Add drained beans, nuts, lemon zest, lemon juice, and thyme. Continue to cook until most of the juice has evaporated, about 3 minutes. Season with salt and fresh ground pepper. Serve immediately.